1. Field of the Invention
The invention relates to a photocopying apparatus of the slit-exposure type, that is to say in which the document to be copied is drawn in front of an elongated exposure window extending perpendicularly to the direction of passage while an optical system projects the image of the part of the document defined in the window, on to a sheet of sensitive paper which passes in the same or reverse direction correspondingly according to the optics of the system. It is drawn by a suitable mechanism into the device for developing the latent image and then discharged from the apparatus.
2. Description of the Prior Art
In known devices, the sheet constituting the document to be copied, generally arranged on a movable exposure carriage, is drawn to pass before the exposure window by a guide device comprising a certain number of pairs of rubber rollers. In each pair of rollers, the two rollers are on parallel axes and are adjacent, under slight pressure, so that, the sheet to be copied, introduced between the rollers of the same pair is thus conventionally gripped between the latter and drawn by their rotary movement. It is then taken up by the subsequent pair of rollers which rotate at the same speed, and so on. The exposure window is situated between two successive pairs of rollers and after complete exposure, is brought back to its starting point by reverse rotation of the rollers.
This device which necessitates recourse to a plurality of pairs of drive rollers and to a complex electrical and electronic control device, obviously requires much labor to manufacture. Moreover, it does not include the possibility of copying a page of a book or of a thick magazine.